1. I prefer them being separate when there's conflict (such as ASOIAF/GOT) but I don't mind them being together when they are just really big franchises (Star Wars, MCU). As long as the minimum number of character/relationship offers is low enough that I can stick to parts of canon I'm familiar with, I don't care if the tagset also includes characters I'm not familiar with.

2. If fandoms are consolidated, I think you should have more character/relationship slots per fandom. No opinion on more fandoms.

3. I am all for relationships.